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Letteratura scientifica selezionata sul tema "Quaternary"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 luglio 2024

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Articoli di riviste sul tema "Quaternary"

Pirrung, Michael, e Bernd Zolitschka. "Quaternary climate evolution". Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 156, n. 4 (1 dicembre 2005): 497–500. http://dx.doi.org/10.1127/1860-1804/2005/0156-0497.

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JUVIGNE, Etienne. "Téphrostratigraphie du Quaternaire en Belgique [Quaternary tephrostratigraphy in Belgium]". Quaternary geology of Belgium: new perspectives 2, n. 1-2 (1 aprile 2000): 73–87. http://dx.doi.org/10.20341/gb.2014.011.

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The main characteristics of Quaternary volcanic ash-falls found in various terrains of Belgium are put together. An exhaustive list of papers dealing with Quaternary tephrostratigraphy in Belgium is presented in an appendix.

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Graham, C. C., e A. Straw. "Quaternary". Geological Society, London, Memoirs 13, n. 1 (1992): 149–53. http://dx.doi.org/10.1144/gsl.mem.1992.012.01.15.

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AbstractThe Quaternary is represented widely over land areas and sea floors around Britain by sediments formed under conditions which ranged from warm temperate to glacial, humid to semi-arid, and which involved glacial, periglacial, fluvial, mass movement, marine and aeolian processes.The distribution of Quaternary sediments has been depicted on maps of the Geological Survey since the 1840s and most recently on the Ordnance Survey Quaternary Map of the United Kingdom, (1977, two sheets) at a scale of 1:625,000. The Oxford Atlas of Britain and Northern Ireland (1963) and the Atlas of Ireland (1979) include Quaternary maps, and Britain is covered by two sheets of the International Quaternary Map of Europe (1967) at a scale of 1:2,500,000. Maps of sea-floor sediments are being published as surveys are completed (Cameron et al. 1987). Stages of the Quaternary sequence as currently established are listed by West (1980) and Bowen et al. (1986).Qla: Quaternary geographyThe maximum extent ever reached by icesheets in southern Britain is better known in the east, and the western limit of 1°30'W is an approximation because definitive deposits are sparsely distributed. The Scilly Islands represent the most southerly point reached by a British icesheet, but the limit across the Celtic Sea is hypothetical, drawn with regard both to the nature of the continental shelf and to the fact that Ireland is known to have been wholly glacierized on at least one occasion. This maximum limit may be diachronous. Bowen et al. (1986) regard it as wholly Anglian, but

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van Geel, Bas, e André Aptroot. "Fossil ascomycetes in Quaternary deposits". Nova Hedwigia 82, n. 3-4 (1 maggio 2006): 313–29. http://dx.doi.org/10.1127/0029-5035/2006/0082-0313.

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Tutin, Winifred Pennington. "Quaternary Ecology". Ecology 74, n. 3 (aprile 1993): 967–68. http://dx.doi.org/10.2307/1940824.

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Clayton, Keith, M. A. J. Williams, D. L. Dunkerley, P. De Dekker, A. P. Kershaw e T. Stokes. "Quaternary Environments". Geographical Journal 161, n. 2 (luglio 1995): 219. http://dx.doi.org/10.2307/3059992.

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Bavec, Miloš. "Quaternary Lives". Geologija 50, n. 2 (27 dicembre 2007): 343–46. http://dx.doi.org/10.5474/geologija.2007.024.

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Tutin, W., L. C. K. Shane e E. J. Cushing. "Quaternary Landscapes." Journal of Ecology 80, n. 2 (giugno 1992): 375. http://dx.doi.org/10.2307/2261028.

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KUMAI, Hisao. "Quaternary Stratigraphy." Quaternary Research (Daiyonki-Kenkyu) 30, n. 3 (1991): 131–40. http://dx.doi.org/10.4116/jaqua.30.131.

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KRISHNAN, G., e A. P. SHIVAPRASAD. "Quaternary multiplexer". International Journal of Electronics 61, n. 3 (settembre 1986): 387–96. http://dx.doi.org/10.1080/00207218608920880.

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Più fonti

Tesi sul tema "Quaternary"

Rhod, Eduardo Luis. "Quaternary CLB a falul tolerant quaternary FPGA". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/72925.

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A diminuição no tamanho dos transistores vem aumentando cada vez mais o número de funções que os dispositivos eletrônicos podem realizar. Apesar da diminuição do tamanho mínimo dos transistores, a velocidade máxima dos circuitos não consegue seguir a mesma taxa de aumento. Um dos grandes culpados apontados pelos pesquisadores são as interconexões entre os transistores e também entre os componentes. O aumento no número de interconexões dos circuitos traz consigo um significativo aumento do cosumo de energia, aumento do atraso de propagação dos sinais, além de um aumento da complexidade e custo do projeto dos circuitos integrados. Como uma possível solução a este problema é proposta a utilização de lógica multivalorada, mais especificamente, a lógica quaternária. Os dispositivos FPGAs são caracterizados principalmente pela grande flexibilidade que oferecem aos projetistas de sistemas digitais. Entretanto, com o avanço nas tecnologias de fabricação de circuitos integrados e diminuição das dimensões de fabricação, os problemas relacionados ao grande número de interconexões são uma preocupação para as próximas tecnologias de FPGAs. As tecnologias menores que 90nm possuem um grande aumento na taxa de erros dos circuitos, na lógica combinacional e sequencial. Apesar de algumas potenciais soluções começara a ser investigadas pela comunidade, a busca por circuitos tolerantes a erros induzidos por radiação, sem penalidades no desempenho, área ou potência, ainda é um assunto de pesquisa em aberto. Este trabalho propõe o uso de circuitos quaternários com modificações para tolerar falhas provenientes de eventos transientes. Como principal contribuição deste trabalho destaca-se o desenvolvimento de uma CLB (do inglês Configurable Logic Block) quaternária capaz de suportar eventos transientes e, na possibilidade de um erro, evitá-lo ou corrigi-lo.
The decrease in transistor size is increasing the number of functions that can be performed by the electronic devices. Despite this reduction in the transistors minimum size, the circuit’s speed does not follow the same rate. One of the major reasons pointed out by researchers are the interconnections between the transistors and between the components. The increase in the number of circuit interconnections brings a significant increase in energy consumption, propagation delay of signals, and an increase in the complexity and cost of new technologies IC designs. As a possible solution to this problem the use of multivalued logic is being proposed, more specifically, the quaternary logic. FPGA devices are characterized mainly by offering greater flexibility to designers of digital systems. However, with the advance in IC manufacturing technologies and the reduced size of the minimum fabricated dimensions, the problems related to the large number of interconnections are a concern for future technologies of FPGAs. The sub 90nm technologies have a large increase in the error rate of its functions for the combinational and sequential logic. Although potential solutions are being investigated by the community, the search for circuits tolerant to radiation induced errors, without performance, area, or power penalties, is still an open research issue. This work proposes the use of quaternary circuits with modifications to tolerate faults from transient events. The main contribution of this work is the development of a quaternary CLB (Configurable Logic Block) able to withstand transient events and the occurrence of soft errors.

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Lizak, Pawel. "Optimal quaternary linear codes". Thesis, University of Salford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308200.

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Grandin, Henrik. "Hybrid Quaternary/Binary Computing". Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305243.

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Due to scaling limitations and the end of Dennard scaling, energy efficiency has become a primary design goal. Approximate computing aims to solve this problem by sacrificing accuracy for efficiency. This project have evaluated a dual mode architecture that gives accuracy when needed and energy efficiency when it is possible. By combining binary and quaternary logic, up to half of the logic could be deactivated whenever absolute correctness is not critical. This project also proposes a hybrid mode, which aims to increase the number of cases where a more energy efficient representation could be used. By combining the two modes through using the more stable binary logic for the bits with higher significance, while at the same time using the energy efficient quaternary logic for the bits with the least significance, energy can still be saved while at the same time drastically limiting the potential size of the error. Simulations have shown that the hybrid mode not only succeeds in decreasing the maximum size of errors, but also reduces the total number of errors, compared to the quaternary mode. Results show increased energy efficiency of 10% without altering the perceived result at all. If we allow for some degradation of the result, the energy efficiency would improve with almost 40%.

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Cattley, Christopher Andrew. "Quaternary nanocrystal solar cells". Thesis, University of Oxford, 2016. http://ora.ox.ac.uk/objects/uuid:977e0f75-e597-4c7a-8f72-6a26031f8f0b.

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This thesis studies quaternary chalcogenide nanocrystals and their photovoltaic applications. A temperature-dependent phase change between two distinct crystallographic phases of stoichiometric Cu₂ZnSnS₄ is investigated through the development of a one pot synthesis method. Characterisation of the Cu₂ZnSnS₄ nanocrystals was performed using absorption spectroscopy, transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). An investigation was conducted into the effects of using hexamethyldisilathiane (a volatile sulphur precursor) in the nucleation of small (<7nm), mono-dispersed and solution-stable quaternary Cu₂ZnSnS₄ nanocrystals. A strategy to synthesize high quality thermodynamically stable kesterite Cu₂ZnSnS₄ nanocrystals is established, which subsequently enabled the systematic study of Cu₂ZnSnS₄ nanocrystal formation mechanisms, using optical characterization, XRD, TEM and Raman spectroscopy. Further studies employed scanning transmission electron microscopy (STEM) energy dispersive x-ray (EDX) mapping to examine the elemental spatial distributions of Cu₂ZnSnS₄ nanocrystals, in order to analyse their compositional uniformity. In addition, the stability of nanocrystals synthesised using alternative ligands is investigated using Fourier transform infrared spectroscopy, without solution based ligand substitution protocol is used to replace aliphatic reaction ligands with short, aromatic pyridine ligands in order to further improve Cu₂ZnSnS₄ colloid stability. A layer-by-layer spin coating method is developed to fabricate a semiconductor heterojunction, using CdS as an n-type window, which is utilised to investigate the photovoltaic properties of Cu₂ZnSnS₄ nanocrystals. Finally, three novel passivation techniques are investigated, in order to optimise the optoelectronic properties of the solar cells to the point where a power conversion efficiency (PCE) of 1.00±0.04% is achieved. Although seemingly modest when compared to the performance of leading devices (PCE>12%) this represents one of the highest obtained for a Cu₂ZnSnS₄ nanocrystal solar cell, fabricated completely under ambient conditions at low temperatures.

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Grun, Rainer Wolfgang. "Contributions to quaternary geochronology". Phd thesis, Canberra, ACT : The Australian National University, 1995. http://hdl.handle.net/1885/145307.

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Souza, Melina Mara de 1984. "Palinologia em sedimentos quaternários, localizados na Estação do Instituto Florestal de Jataí, SP". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287276.

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Orientadores: Frésia Soledad Ricardi Torres Branco, André Jasper
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
Made available in DSpace on 2018-08-16T07:38:35Z (GMT). No. of bitstreams: 1 Souza_MelinaMarade_M.pdf: 2503896 bytes, checksum: 9cde6f27f9a424cade3629e5e8b1b0b2 (MD5) Previous issue date: 2010
Resumo: O estudo de uma trincheira coletada em um meandro abandonado, as margens do Rio Mogi-Guaçú, em uma área coberta por Cerrado, na Estação do Instituto Florestal de Jataí, Município de Luís Antônio (SP), permitiu realizar estudos pertinentes a evolução paleoambiental e, possíveis inferências paleoclimáticas, ao longo dos últimos 10.251 anos A.P. As interpretações paleoecológicas foram baseadas nas análises dos fragmentos de carvão, assembléias de palinomorfos, e análises isotópicas. A partir das análises isotópicas foi possível estabelecer a cronologia dos eventos ocorridos no local, por meio de análises de 14C, e a distinção dos valores isotópicos de ? 13C, que possibilitou a interpretação e diferenciação das variações da vegetação de plantas C3 (árvore) e C4 (gramínea). A análise palinológica, foi baseada em diagrama de perfil de porcentagem e concentração dos palinomorfos preservados no depósito estudado, o que permitiu estabelecer, através de dados estatísticos a determinação e distribuição da vegetação durante o Holoceno na área de estudo. Para análise dos fragmentos de carvão, foi feita á identificação e separação dos fragmentos encontrados em cada nível, em estereomicroscópio e fotografados no MEV, estabelecendo inferências e informações importantes tanto no domínio das variações paleoambientais, como paleoclimáticas e paleoincêndios. Os resultados das análises palinológicas, isotópicas e fragmentos de charcoals apontaram para um clima mais seco que o atual entre 10.251 e 10.186 anos A.P. com altas taxas de fragmentos de carvão, indicando períodos de ocorrência de paleoincêndios e de abertura florestal, onde valores de ? 13C em torno de -14,26¿, mostram a presença de plantas C4 (gramíneas), uma vegetação mais aberta que a atual. Entre 10.186 e 2.096 anos A.P. onde ocorreu um empobrecimento isotópico e uma mistura de plantas C3 e C4, com o aumento da freqüência de grãos de pólen indicadores de Cerrado como Byrsonima e Dydimopanax, podemos inferir que nesta fase o clima esteve mais úmido, e a vegetação mais fechada. Após 2.096 anos A.P. até os dias atuais as condições paleoclimáticas seriam as mesmas, caracterizada como cerradão, que possui formações florestais com espécies de Cerrado sentido restrito, sem nenhum registro de fragmentos de carvão e o aparecimento de grãos de pólens de Cerrado
Abstract: The study collected a trench in an abandoned meander on the banks of Mogi-Guaçú River in an area covered by Cerrado at the Station of the Instituto Florestal de Jataí, in Municipality of Luis Antonio (SP). It was allowed to conduct relevant studies and palaeoenvironmental evollution, possible paleoclimatic inferences, over the past 10.251 years A.P. The paleoecological interpretations were based on analysis of charcoal fragments, palynomorph assemblages, and isotopic analysis. From the isotopic analysis it was possible to establish the chronology of events on site, by analysis of 14C, and the distinction of the isotopic values of ? 13C, which facilitated the interpretation and differentiation of changes in vegetation from C3 plants (trees) and C4 ( grass). Pollen analysis were based on census profile of the percentage and concentration of the palynomorphs preserved in the deposit studied allowing to establish, through statistical data, the determination and distribution of vegetation during the Holocene in the study area. To analyze the charcoals, it was made the identification and the fragments found in each level were separated by a stereomicroscope and photographed in the MEV, establishing inferences and important information, both in the field of palaeoenvironmental variations, as paleoclimate and paleofires. The results of pollen analysis, isotopic and charcoals fragments pointed to a drier climate than nowadays, from 10.251 to 10.186 years A.P. with high rates of charcoals fragments, indicating periods of paleofires occurrence and open forest where values around ? 13C -14,26 ¿, indicated the presence of C4 plants (grasses), more open vegetation than at present. From 10.186 to 2.096 years A.P. occurred an isotopic depletion and a mixture of C3 and C4 plants, increasing pollen frequency indicators of Cerrado and Byrsonima Dydimopanax. At this stage the climate was wetter and the vegetation closer. After 2.096 years A.P. until nowadays, the paleoclimatic conditions have been the same, characterized as Cerrado, which has forest with species of Cerrado sensu stricto with no record of charcoals and the appearance of pollen of Cerrado
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências

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Hardiman, J. C. "Quaternary volcanism on Nisyros, Greece". Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603684.

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This thesis describes the volcanic deposits on Nisyros, Aegean sea, Greece and uses them to understand volcanic processes and the evolution of the island. Nisyros is a small (42 km² in area) symmetric stratovolcano which has evolved on the eastern end of the Aegean volcanic arc over the last 200 ka of the Quaternary. The first volcanic activity was submarine. This left a layer of pillow larvas of basaltic-andesite composition overlying the Tertiary sedimentary basement of the Aegean. Subsequent volcanic activity was subaerial, and over 20 lava and pyroclastic eruptions of basaltic-andesite to rhyolite composition led to the formation of a stratovolcano. The younger eruptions were rhyolitic and the magma emitted is estimated to be of the order of a few km³ in volume. These eruptions led to the formation of a 10 km² in area caldera which now dominates the centre of the island. A suite of domes were extruded progressively on western side of the caldera floor with field appearances suggesting activity continuing into the Holocene. The activity documented in historical records and seen at the present day is entirely phreatic and is the expression of a geothermal reservoir at a shallow depth below the caldera floor. The aims of this project were to describe the volcanic stratigraphy, to use the xenolith suite to understand magmatic and vent erosion processes, and to use the deposits from the three rhyolite eruptions to understand the youngest volcanic history of the island and timing of the caldera formation. Fieldwork was used to deduce the stratigraphy of the island. The stratocone succession consists of 3 cycles that start with basaltic-andesite to andesite lavas (BA&AI, BA&AII. BA&AIII) and pyroclastic deposits (SPI, SPII, SPIII) and proceed to dacite to rhyolite lava extrusions (DI, DII and RI, DIII) and pyroclastics (MSP, PK, LP).

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Franke, Jasper Gideon. "Networks of the late Quaternary". Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19994.

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In den letzten Jahren erfreuen sich komplexe Netzwerke einer zunehmenden Beliebtheit, um Zusammenhänge und Strukturen in hoch-dimensionalen Datensätzen zu analysieren. Im Unterschied zu vielen anderen Forschungsgebieten wurden sie jedoch selten auf Paläoklima-Daten angewandt, obwohl die steigende Anzahl an veröffentlichen Zeitreihen die Nutzung effizienter Methoden multivariater Analyse ermöglicht. Die Resultate der wenigen Studien, in denen Netzwerkmethoden und Paläoklima-Daten kombiniert wurden, sind außerdem geprägt von niedriger Robustheit und hohen Unsicherheiten. Dies steht im Zusammenhang zu der niedrigen Anzahl und Auflösung der Zeitreihen als auch den Unsicherheiten, die den meisten Paläoklima-Rekonstruktionen zu eigen sind. In dieser Doktorarbeit schlage ich verschiedene Wege vor, um diese Probleme zu überwinden, indem verlässlichere, quantitative Resultate ermöglicht werden, unter anderem indem die Datenunsicherheiten explizit in die Analyse mit einbezogen werden. Zu diesem Zweck präsentiere ich vier Fallstudien mit einem Fokus auf zwei Zeiträume, das späte Holozän (die letzten zweitausend Jahre) und den Übergang von der letzten Kaltzeit zur aktuellen Warmzeit, die letzte glaziale Termination. Alle diese Studien legen einen räumlichen Fokus auf den Nordatlantik, eine Schlüsselregion globaler Klimavariabilität. Ich beschränke mich hierbei auf zwei Methoden, eine der netzwerkbasierten Zeitreihenanalyse, Sichtbarkeitsgraphen genannt, und eine der räumlichen Analyse, sogenannte Klimanetzwerke. Neben Erweiterungen von existierende Methoden, schlage ich auch neue Wege vor, um verlässliche Resultate auch für Zeitreihen mit hohen Unsicherheiten zu erhalten. Diese Fallstudien demonstrieren, dass Netzwerkmethoden auch für die Analyse von Paläoklima-Daten nützlich sein können. Sie sind daher ein weiterer Schritt hin zu einer künftigen Anwendung durch eine größere Anzahl an Forschenden.
In recent years, complex networks have become an increasingly popular tool to analyse relationships and structures in high-dimensional data sets in a variety of research fields. They have, however, rarely been applied to paleoclimate data sets, even though the growing number of published records demands efficient tools of multivariate analysis. The few published results that combine network methods and paleoclimate proxies are often not robust or have high uncertainty levels, linked tothe low dimensionality, resolution and the large uncertainties of most particulate time series. In this thesis, I propose several ways to overcome these issues in order to obtain reliable and quantitative results from network based tools by taking the particularities of paleoclimate data into account. For this purpose, I present four case studies, focusing on two time periods, the late Holocene (last two millennia) and the transition from the last ice age to the recent warm period, the last deglaciation. These studies are all related to the North Atlantic, a key region in multi-decadal to millennial scale climate variability. I primarily use two methods, one of network based time series analysis named visibility graphs and one of spatial analysis, so called limate networks. I have both further developed existing methods, but also propose new ways to yield reliable results when dealing with highly uncertain paleoclimate data. The case studies demonstrate the usefulness of network based data analysis to study patterns of regional climate variability. Hence, this work is another step in bringing network based approaches to a larger audience and towards a wider application of these methods.

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Ghazoui, Zakaria. "Late Quaternary Seismicity and Climate in the Western Nepal : Himalaya". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU026/document.

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L'Himalaya résultant de la collision indo-asiatique, dans laquelle l'Inde plonge sous le Tibet, initie régulièrement des tremblements de terre destructeurs dont la plupart sont mortel pour les communautés népalaises et limitrophes. Telle une muraille séparant les plaines d’Inde et le haut plateau du Tibet, l’Himalaya façonne la circulation atmosphérique, affectant tant le climat régional que global. Cette thèse vise à se pencher sur l'histoire et l'évolution peu connue du climat et de la sismicité de l'Himalaya, dans une des régions les moins peuplées et la plus reculées du Népal occidental. Dans le contexte de changements climatiques et environnementaux, l'un des aspects les moins bien élucidés de l'histoire de l'Himalaya au cours du Quaternaire supérieur est celui de l'extension des glaciers ainsi que leurs impacts sur l'évolution du paysage. En nous appuyant sur des observations de terrain, sur des datations par nucléides cosmogéniques (10Be) ainsi que des observations satellitaires, nous avons pu estimer l'étendue maximale des glaciers durant le dernier maximum glaciaire. Soutenant ainsi l'hypothèse suivant laquelle la présence de glacier fut relativement plus étendue à l'échelle du Népal occidental mais pas de l’ordre d’une calotte glaciaire. Sur le plan sismologique, l’enjeu à la fois sociale, économique et politique de l’occurrence d’un séisme de magnitude plus élevée que le récent séisme de 2015 dont l’épicentre se situe près de la ville de Gorkha constitue une préoccupation majeure et motive en grande partie cette thèse. Le dernier séisme majeur ayant rompu le Main Frontal Thrust de magnitude supérieure à 8 (Mb) s’est déroulé le 6 juin 1505 et a considérablement impacté la population népalaise et environnante. Le caractère singulier du Népal occidental s’exprimant ainsi par l’hypothèse de la présence d’un hiatus sismique s’étendant sur plus de 500 ans sur base d’archives historiques et d’études paléosismologiques. Dans cette perspective, cette thèse se penche sur deux questions majeures relatives au comportement sismique de l'Himalaya : d'une part, l'hypothèse d'une lacune sismique dans l'Himalaya central et, d'autre part, de la distribution temporelle des séismes au cours de la fin du Quaternaire. A cette fin, une nouvelle approche de recherche, indépendamment du recours aux tranchées paléosismiques, a été mise en œuvre en Himalaya. En utilisant les lacs comme paleoseismomètre, au travers de la collecte de carottes sédimentaires, nous avons pu affiner la résolution temporelle et déceler des séismes à ce jours non répertorié dans les basses de données accessible et ce sur une échelle de 700 ans. La mise en évidence de séismes important (Mw>6.5) non répertorié indique que le Népal occidental connait une activité sismique comparable au centre du Népal et remet en question l’hypothèse d’un gap sismique au centre de l’Himalaya. Sur base d'une carotte sédimentaire plus longue provenant du même lac, nous avons étudié la distribution temporelle des séismes sur une période de 6000 ans, permettant ainsi de mettre en évidence le caractère aléatoire de l’occurrence des séismes constituant un changement de paradigme là où notion de cycle sismique est encore prépondérante. La mise en évidence du caractère aléatoire de l’occurrence des séismes tant à courte échelle de temps (instrumentale) qu’à l’échelle du Quaternaire infirme l’hypothèse du gap sismique au centre de l’Himalaya et mets en évidence le risque permanent pour le million de personnes concernées. Cette thèse s’achève en se penchant sur une possible relation à l’échelle globale entre la variation de taux de séismicité et les changements climatiques au cours de l’Holocène. Nous constatons ainsi que la sismicité globale connu des périodes de séismes accrue sur 7000 ans. Ces périodes de plus fortes activités semblent être synchrone avec la somme des avancées glaciaires de l'Holocène moyen et supérieur
The Himalayan collision, in which India underthrusts below Tibet, regularly produces major destructive earthquakes in Nepal and its neighboring countries, most of which are fatal to nearby communities. As a wall dividing the Indian plains and the Tibetan plateau, the Himalaya also significantly modifies the atmospheric circulation, affecting both the local and global climate. This thesis explores the poorly known Quaternary history and evolution of Himalayan climate and seismicity, more particularly in the least populated and most remote region of Western Nepal. In terms of climate and environmental change, one of the least understood aspects of Himalayan history during the late Quaternary is the extension of glaciers and their impacts on landscape evolution. Based on field observations, cosmogenic nuclide dating (10Be) and satellite observations, we estimated the maximum extent of glaciers during the Last Glacial Maximum, which supports the hypothesis of a relatively large glacier cover, but not of an extended ice cap, at the scale of Western Nepal. In terms of seismology, the social, economic and political implications of the occurrence of an earthquake of higher magnitude than the recent earthquake of 2015, whose epicenter is located near the city of Gorkha, is a major concern and largely motivates this thesis. The last major earthquake of magnitude greater than 8 (Mb) took place on 6 June 1505 and had a profound impact on the Nepalese population and the surrounding area. In Western Nepal the 1505 event was the last earthquake that ruptured the Main Frontal Thrust according to historical archives and paleoseismological studies, which gave rise to the concept of a seismic gap in western Nepal and adjacent areas in northern India. With this in mind, this thesis addresses two major issues on the Himalayan seismic behavior: on the first hand is the hypothesis of a seismic gap in the central Himalaya and on the second the temporal distribution of earthquakes during the late Quaternary. For this purpose, a new research approach independent of paleoseismic trenches was applied in the Himalaya. By using lakes as paleoseismometers, we were able to refine the temporal resolution and identify earthquakes that had not yet been documented in the accessible databases on a 700-year scale. Our results from Lake Rara highlight significant previously-unknown earthquakes (Mw>6.5) and they reveal that Western Nepal is seismically as active as central Nepal. Furthermore, they call into question the hypothesis of a seismic gap in the central Himalaya. Based on a longer sediment core from the same lake, we studied the temporal distribution of earthquakes over a period of 6000 years, which has highlighted the random nature of the occurrence of earthquakes, constituting a paradigm shift where the notion of seismic cycle is still prevalent. The random nature of the occurrence of earthquakes both on short (instrumental) and Quaternary time scales disproves the hypothesis of the seismic gap in the central Himalaya and underlines the permanent risk for the million people of concern. The final part of this thesis addresses the possible global relationship between seismic rate fluctuations and climate change during the Holocene. Our results show that the global seismicity clustered over 7000 years and appears to be synchronous with the sum of glacial advances through the Mid and Late Holocene

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Pernas, Vallès Jaume. "On Quaternary Linear Reed-Muller Codes". Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/96434.

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A la literatura recent hi podem trobar la introducció de noves famílies de codis de Reed- Muller quaternaris lineals RMs. Les imatges d’aquests nous codis a través del mapa de Gray són codis binaris Z4-lineals que comparteixen els paràmetres i les propietats (longitud, dimensió, distància mínima, inclusió, i relació de dualitat) amb la família de codis de Reed- Muller binaris lineals. El kernel d’un codi binari C es defineix com K(C) = {x 2 Zn2 : C + x = C}. La dimensió del kernel és un invariant estructural per els codis binaris equivalents. Part d’aquesta tesi consisteix en establir els valors de la dimensió del kernel per aquestes noves famílies de codis de Reed-Muller Z4-lineals. Tot i que dos codis Z4- lineals no equivalents poden compartir el mateix valor de la dimensió del kernel, en el cas dels codis de Reed-Muller RMs aquest resultat es suficient per donar-ne una classificació completa. Per altra banda, un codi quaternari lineal de Hadamard C, és un codi que un cop li hem aplicat el mapa de Gray obtenim un codi binari de Hadamard. És conegut que els codis de Hadamard quaternaris formen part de les famílies de codis quaternaris de Reed- MullerRMs. Definim el grup de permutacions d’un codi quaternari lineal com PAut(C) = { 2 Sn : (C) = C}. Com a resultat d’aquesta tesi també s’estableix l’ordre dels grups de permutacions de les famílies de codis de Hadamard quaternaris. A més a més, aquests grups són caracteritzats proporcionant la forma dels seus generadors i la forma de les òrbites del grup PAut(C) actuant sobre el codi C. Sabem que el codi dual, en el sentit quaternari, d’un codi de Hadamard és un codi 1-perfecte estès. D’aquesta manera els resultats obtinguts sobre el grup de permutacions es poden transportar a una família de codis quaternaris 1- perfectes estesos
Recently, new families of quaternary linear Reed-Muller codes RMs have been introduced. They satisfy that, under the Gray map, the corresponding Z4-linear codes have the same parameters and properties (length, dimension, minimum distance, inclusion, and duality relation) as the codes of the binary linear Reed-Muller family. The kernel of a binary code C is K(C) = {x 2 Zn2 : C + x = C}. The dimension of the kernel is a structural invariant for equivalent binary codes. In this work, the dimension of the kernel for these new families of Z4-linear Reed-Muller codes is established. This result is sufficient to give a full classification of these new families of Z4-linear Reed-Muller codes up to equivalence. A quaternary linear Hadamard code C is a code over Z4 that under the Gray map, the corresponding Z4-linear code is a binary Hadamard code. It is well known that quaternary linear Hadamard codes are included in the RMs families of codes. The permutation automorphism group of a quaternary linear code C of length n is defined as PAut(C) = { 2 Sn : (C) = C}. In this dissertation, the order of the permutation automorphism group of all quaternary linear Hadamard codes is established. Moreover, these groups are completely characterized by providing their generators and also by computing the orbits of their action on C. Since the dual of a Hadamard code is an extended 1-perfect code in the quaternary sense, the permutation automorphism group of the quaternary linear extended 1-perfect codes is also established.

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Più fonti

Libri sul tema "Quaternary"

Cormier, Chantal. Vocabulaire canadien du Quaternaire =: Canadian Quaternary vocabulary. [Ottawa]: Secrétariat d'Etat du Canada, Energie, mines et ressources Canada, 1992.

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Cormier, Chantal. Vocabulaire canadien du quaternaire =: Canadian Quaternary vocabulary. [Ottawa]: Secrétaire d'État du Canada = Dept. of the Secretary of State of Canada, 1992.

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Noller, Jay Stratton, Janet M. Sowers e William R. Lettis, a cura di. Quaternary Geochronology. Washington, D. C.: American Geophysical Union, 2000. http://dx.doi.org/10.1029/rf004.

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Delcourt, Hazel R., e Paul A. Delcourt. Quaternary Ecology. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3104-9.

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K, Shane Linda C., Cushing Edward J. 1933-, National Science Foundation (U.S.). Climate Dynamics Program. e University of Minnesota, a cura di. Quaternary landscapes. Minneapolis: University of Minnesota Press, 1991.

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H, Birks Hilary, a cura di. Quaternary palaeoecology. Caldwell, N.J: Blackburn Press, 2004.

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K, Shane Linda C., e Cushing Edward John, a cura di. Quaternary landscapes. London: Belhaven Press, 1991.

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Bradley, Raymond S. Quaternary paleoclimatology. New York: Chapman & Hall, 1997.

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J, Williams M. A., a cura di. Quaternary environments. London: Edward Arnold, 1993.

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J, Williams M. A., a cura di. Quaternary environments. 2^a ed. New York: Arnold, 1998.

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Capitoli di libri sul tema "Quaternary"

Hine, N., e P. P. E. Weaver. "Quaternary". In Calcareous Nannofossil Biostratigraphy, 266–83. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-4902-0_9.

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Weik, Martin H. "quaternary". In Computer Science and Communications Dictionary, 1389. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_15257.

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Head, Martin J. "Quaternary". In Handbook of the Anthropocene, 373–78. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-25910-4_57.

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Adachi, Sadao. "Quaternary Alloys". In Optical Constants of Crystalline and Amorphous Semiconductors, 347–410. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-5247-5_30.

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Goudie, Andrew S. "The Quaternary". In World Geomorphological Landscapes, 41–55. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-38957-4_3.

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Ehlers, Jürgen, e Philip Gibbard. "Quaternary Glaciation". In Encyclopedia of Earth Sciences Series, 873–82. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-2642-2_423.

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Martínez, Sergio, Claudia J. del Río e Alejandra Rojas. "Quaternary Mollusks". In Biogeography of the Quaternary Molluscs of the Southwestern Atlantic Ocean, 17–32. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6055-4_5.

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Weik, Martin H. "quaternary operator". In Computer Science and Communications Dictionary, 1389. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_15258.

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Weik, Martin H. "quaternary signal". In Computer Science and Communications Dictionary, 1389. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_15260.

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Gooch, Jan W. "Quaternary Structure". In Encyclopedic Dictionary of Polymers, 919. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_14629.

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Atti di convegni sul tema "Quaternary"

GÖNNENWEIN, F., P. JESINGER, M. MUTTERER, A. M. GAGARSKI, G. A. PETROV, W. H. TRZASKA, V. NESVIZHEVSKI e O. ZIMMER. "QUATERNARY FISSION". In Proceedings of the International Conference. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812778321_0019.

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GÖNNENWEIN, F., P. JESINGER, M. MUTTERER, A. M. GAGARSKI, G. A. PETROV, W. H. TRZASKA, V. NESVISHEVSKY e O. ZIMMER. "QUATERNARY FISSION". In Proceedings of the International Workshop. WORLD SCIENTIFIC, 2001. http://dx.doi.org/10.1142/9789812811127_0022.

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Khan, Mozammel H. A. "Quaternary quantum algorithm for determining properties of quaternary logic function". In 2011 14th International Conference on Computer and Information Technology (ICCIT). IEEE, 2011. http://dx.doi.org/10.1109/iccitechn.2011.6164771.

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Jahangir, Ifat, Dihan Md Nuruddin Hasan, Nahian Alam Siddique, Shajid Islam e Md Mehedi Hasan. "Design of quaternary sequential circuits using a newly proposed quaternary algebra". In 2009 12th International Conference on Computer and Information Technology (ICCIT). IEEE, 2009. http://dx.doi.org/10.1109/iccit.2009.5407139.

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Mandal, Sandip, Goutam Kumar Maity, Animesh Bhattacharya e Kazi A. H. TaslimArif. "All-optical quaternary MIN gate and quaternary delta literals using MZI". In 2017 International Conference on Inventive Communication and Computational Technologies (ICICCT). IEEE, 2017. http://dx.doi.org/10.1109/icicct.2017.7975211.

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Borkute, Deepti, e P. K. Dakhole. "Synthesizable Quaternary logic blocks". In 2016 International Conference on Computing Communication Control and automation (ICCUBEA). IEEE, 2016. http://dx.doi.org/10.1109/iccubea.2016.7860120.

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Jesinger, P. "Ternary and quaternary fission". In The tenth international symposium on capture gamma-ray spectroscopyand related topics. AIP, 2000. http://dx.doi.org/10.1063/1.1361475.

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Parammel, Aboobacker, e Viji Maniyil. "On quaternary resilient functions". In INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN MATHEMATICS AND COMPUTATIONAL ENGINEERING: ICRAMCE 2022. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0156723.

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Picek, Stjepan, Karlo Knezevic, Luca Mariot, Domagoj Jakobovic e Alberto Leporati. "Evolving Bent Quaternary Functions". In 2018 IEEE Congress on Evolutionary Computation (CEC). IEEE, 2018. http://dx.doi.org/10.1109/cec.2018.8477677.

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Khan, Mozammel H. A. "Synthesis of incompletely specified multi-output quaternary function using quaternary quantum gates". In 2007 10th International Conference on Computer and Information Technology (ICCIT 2007). IEEE, 2007. http://dx.doi.org/10.1109/iccitechn.2007.4579405.

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Rapporti di organizzazioni sul tema "Quaternary"

Josenhans, H. W., e J. Zevenhuizen. Quaternary geology I, Labrador sea, Quaternary history. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1989. http://dx.doi.org/10.4095/127156.

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Stieve, A. Quaternary investigation. Office of Scientific and Technical Information (OSTI), maggio 1991. http://dx.doi.org/10.2172/5617180.

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Stieve, A. Quaternary investigation. Office of Scientific and Technical Information (OSTI), maggio 1991. http://dx.doi.org/10.2172/10127836.

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Kaj, Lennart, Petra Wallberg e Eva Brorström-Lundén. Quaternary ammonium compounds. Nordic Council of Ministers, novembre 2014. http://dx.doi.org/10.6027/tn2014-556.

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Vincent, J. S. Quaternary Geology Subdivision. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1990. http://dx.doi.org/10.4095/305385.

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McNeely, R. N. Quaternary Environments Subdivision. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1990. http://dx.doi.org/10.4095/305386.

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Clague, J. J. Quaternary Tectonic Setting [Chapter 1: Quaternary Geology of the Canadian Cordillera]. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1989. http://dx.doi.org/10.4095/127915.

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Clague, J. J. Quaternary Sea Levels [Chapter 1: Quaternary Geology of the Canadian Cordillera]. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1989. http://dx.doi.org/10.4095/127931.

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MW Dashiell, JF Beausang, H Ehsani, GJ Nichols, DM Depoy, LR Danielson, P Talamo et al. Quaternary InGaAsSb Thermophotovoltaic Diodes. Office of Scientific and Technical Information (OSTI), marzo 2006. http://dx.doi.org/10.2172/881293.

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Prest, V. K. Quaternary ice sheet extent. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1987. http://dx.doi.org/10.4095/126960.

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